Work will proceed on the development of somatic cell genetic systems of genetic analysis in mammalian species. We wil continue to employ techniques such as cell hybridization, microcell transfer of chromosomes, and chromosome mediated gene transfer. Analysis of the chromosome mediated gene transfer system will be emphasized. Special attention will be given to DNA transformation using mammalian and viral DNAs. In addition to these new somatic cell genetic procedures, we shall improve on our capacity to map gene sequences using nucleic acid hybridization methodologies. It will be our aim to use these techniques to map the immunoglobulin genes and endogenous viral sequences.